Pathology specimens of eligible stage II-III NSCLC patients were immunohistochemically stained with PD-1 and PD-L1 antibodies. Patient files and digital records were retrospectively reviewed for demographic and clinical features such as age, gender, smoking status, Eastern Cooperative Oncology Group (ECOG) performance status (PS), histological tumor subtype, applied chemotherapeutic types and their dates and survival data. Statistical analyses were performed to evaluate prognostic effects of staining status of PD-L1 and PD-1 in tumor cells and PD-L1 in tumor infiltrating inflammatory cells.
In a total 74 patients, 45.9% of them were positive for PD-L1 in tumor cells, 67.9% positive for PD-L1 in tumor infiltrating inflammatory cells and 83.8% positive for PD-1 in tumor cells (p>0.05). There was a statistically significant relationship between the positive staining of PD-L1 tumor cells and increased overall survival (OS) in univariate analysis (3-year OS; PD-L1(+) 76.6% vs PD-L1(-) 41%, p=0.031). In multivariate analysis only stage and ECOG PS were statistically significant.
PD-L1 positivity in tumor cells was a positive prognostic factor for OS in patients with stage II and III NSCLC.